WikiLeaks reacted by moving the website from computers in Sweden to those of Amazon Web Services. Amazon has vast banks of computers that can be rented on a self-service basis to meet surges in traffic.

But that move exposed WikiLeaks to legal and political pressure.

“WikiLeaks servers at Amazon ousted. Free speech the land of the free — fine our $ are now spent to employ people in Europe,” the organization said Wednesday in a posting on the Twitter messaging service.

“If Amazon are so uncomfortable with the first amendment, they should get out of the business of selling books,” WikiLeaks said in another tweet.

Amazon.com would not comment on its relationship with WikiLeaks.

Amazon’s decision to pull down the server apparently began with a call from a staff member of the Homeland Security and Government Affairs Committee, according to Leslie Phillips, Lieberman’s spokeswoman.

Phillips said the staffer inquired about news reports that Amazon was hosting Wikileak’s website.

“And the inquiry ended with Amazon announcing that it had ceased” to host the website, Phillips said.

“The company’s decision to cut off WikiLeaks now is the right decision and should set the standard for other companies WikiLeaks is using to distribute its illegally seized material,” Lieberman said in a statement. He added that he would have further questions for Amazon about the affair.

As an organization, WikiLeaks has no firm geographic base, but founder Julian Assange sought to establish residency in Sweden to take advantage of laws protecting those who funnel information to the media. However, authorities rejected his application for a residency permit.

Swedish police are now seeking to arrest Australian-born Assange based on allegations of sexual assault stemming from his stay in the country. Assange has denied the charges.

Swedish police issued an international arrest warrant on Wednesday, though they haven’t filed formal charges. Assange’s whereabouts are unknown.

The charges were brought by two Swedish women in August after what both described as consensual sexual encounters in Sweden that escalated into something unwanted and illegal. Assange, who has long expressed fear of reprisal from the United States and other governments, denied anything but consensual sex and suggested that the two women were part of a plot to smear his name and undermine his campaign to get government secrets into the open.

Before the women came forward, Assange had sought a Swedish residence visa, hoping to benefit from the country’s strong protection of press freedoms. But since then, he has been traveling constantly and staying below the radar, popping up in London, appearing on a videoconference in Amman, Jordan, and answering questions from Time magazine via Skype.

While Assange stayed out of sight, his Stockholm lawyer, Bjorn Hurtig, filed an appeal Wednesday against the Swedish government’s arrest order. At the same time, his London attorney, Mark Stevens, said the Stockholm prosecutor’s tactics show that she is out to get Assange for more than legal reasons.

One news report suggested that Assange is considering asking for asylum in Switzerland. But that country is known for keeping secrets, so that seemed an unlikely solution. Moreover, WikiLeaks has announced that its next big project is to reveal the confidential documents of a major bank, which could make the land of numbered accounts an awkward haven for Assange.

Seattle Times Washington Bureau reporter Kyung M. Song contributed to this report.